Preeclampsia, the third leading cause of maternal mortality in the United States, is an important cause of preterm delivery, fetal growth retardation, and perinatal mortality. Uteroplacental hypoperfusion is thought to be the primary defect in preeclampsia. Endothelial cell damage is also important in the pathogenesis of preeclampsia. Previous investigators have focused on the cause of these vascular insults. Findings from several disciplines indicate that preeclampsia is associated with excessive lipid peroxidation, oxidant-antioxidant imbalance, as well as an imbalance in n-3 and n-6 polyunsaturated fatty acids, and in thrombooxane and prostacyclin synthesis. Presently it is unknown whether these features precede preeclampsia or are secondary to the disease process. The authors propose to conduct a prospective cohort study of pregnant nulliparous women. The overall aim of the proposed research is to evaluate whether, and to what extent, maternal intake of dietary marine fatty acids and antioxidant vitamins are associated with risk of preeclampsia. The authors will collect maternal blood and urine specimens from a cohort of 1500 women during the first trimester of pregnancy. At the same time, information regarding medical and behavioral characteristics will be collected by interview. Medical records will be reviewed in order to collect information regarding pregnancy outcome. Blood and urine specimens will be processed and stored at -70C until analysis. Maternal intake of marine fatty acids and antioxidant vitamins will be assessed using biochemical and dietary methods. Eicosanoids and indicators of lipid peroxidation will also be evaluated. Using a nested case-cohort sampling design, the authors will identify 90 women with preeclampsia and an equal number of women with gestational hypertension. One hundred and fifty women randomly selected from the entire study cohort (N- 1500) will serve as a single reference group for all individuals sampled. Statistical analyses will focus on determining: (1) the extent to which lipid peroxidation and eicosanoid synthesis in the first trimester are associated with subsequent risk of preeclampsia and gestational hypertension, respectively; and (2) whether these metabolic factors are associated with maternal diet. The investigators state that clinical applications of study findings may result in early identification of women at risk of preeclampsia and an effective intervention.